Elastic vibration isolation mounting with integral hydraulic damping and a rigid partition with an adjustable passage for conducting fluid

ABSTRACT

Elastic anti-vibration isolation apparatus with integrated hydraulic damping, consisting of a thick conical membrane of elastomer compound bonded to internal and external rigid frames, and crimped in a casing containing a damping liquid, characterized by the fact that the rigid partition which separates the variable volume chamber from the expansion space has a passage for the damping liquid realized in one or two parts, the dimensions of which can be adjusted by grinding or lathe-working at least one of the components, base or cover, of the rigid partition, or by the insertion of shims between the constituent parts, thereby making it possible, using a set of similar components, to realize a range of elastic mountings with damping characteristics adapted to desired utilization frequencies.

This is a division, of application Ser. No. 07/177,583, filed on Apr. 4,1988, now U.S. Pat. No. 4,909,490.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to anti-vibration, isolation devices formachines, in particular elastic mountings for automobile motors or thecabs of large trucks. It relates to high-flexibility mountings withintegrated hydraulic damping, increasing the apparent rigidity in a verylimited range of rather low frequencies, by means of a column of liquidwhich is very long in relation to its cross section. The resonance ofthis column counteracts large amplitude displacements, but does notdeleteriously affect, to any substantial degree, the elastic filtering ahigher frequencies.

A range of such elastic mountings is generally made possible by means ofa thick conical elastomer membrane which, when bonded to a supportcasing and a central framework to fasten it to the housing to besuspended, e.g., the power unit, encloses a chamber containing a dampingliquid forced into an expansion space, under low pressure, through adevice with a long inertial column, with the major portion of thevertical load being borne by deformation of the elastomer constitutingthe conical membrane.

French Patent Nos. 2,443,615, 2,462,618, 2,467,724 and 2,511,105(Peugeot) describe devices which fit this definition and which have theadvantage of being integratable into the elastic apparatus with adamping column, which is fitted in a rigid wall immersed in thehydraulic circuit. Thus constituted, the device after being sealed,e.g., by crimping on an attachment cover for the casing, of themounting, thereby manifests itself as a one-piece component.

Various improvements have been made to these devices. For example, thedevice based on a hydrodynamic braking nozzle (French Patent No.2,430,546 to Chrysler) includes a displacement of liquid aided by aresonant mass, acting as an inertial damper Others relate to the use ofthe mass of the liquid itself, and an adjustment of the characteristicsthereof, thereby making possible a low rigidity in response tovibrations at frequencies higher than 25 Hz. Low rigidity in thisfrequency range is effective for general soundproofing, and alsoprovides good damping at the suspension frequencies, that is, in therange of 5 to 15 Hz, where disturbances become noticeable to passengers,as soon as the amplitude of the movements communicated to the supportedstructure exceeds one millimeter.

French Patent No. 2,575,253 for this type of hydraulic shock absorber,called a "column mounting", specifies the simultaneous existence of asecondary passage having different throttling characteristics than theprincipal throttling passage.

An analysis of the prior art shows that it apparently does not includehydroelastic mountings with a long liquid column which is possibly evenlonger than the length of an annular passage and which passage caneasily be adjusted to accommodate the hydroelastic mounting.

All of the above-mentioned patents are hereby expressly incorporated byreference as if the entire contents thereof were fully set forth herein.

2. Object of the Invention

The object of the invention is to provide a hydroelastic mounting with astructure having a passage for receiving the damping liquid, whichpassage is housed in the rigid partition between the variable volumechamber and the expansion space of a hydroelastic mounting. The lengthand/or cross section of this passage can be adjusted to substantially,precisely regulate the strokes and frequencies necessary for use inparticular applications, by acting on the mass of liquid contained inthis passage and on the surface of the boundary layer sheared during thealternating movements of the liquid.

SUMMARY OF THE INVENTION

Using identical constituents, with the exception of the rigid partition,i.e., for the same dimensions of the variable volume chamber and theexpansion space, and for the same rigidity of the thick conical membraneconstituting the deformable wall, the invention proposes to create arange of hydroelastic mountings with damping characteristics adapted toeach application, under economic conditions which allow fabrication insmall quantities, by acting on the parameters of the column of dampingliquid, i.e., its cross section and/or its length.

The elastic anti-vibration isolation mounting with integrated hydraulicdamping which is the object of the invention is characterized by thefact that:

it comprises a passage, consisting of one or two parts, and designed tocontain the damping liquid;

this passage, when it consists of a single part, is constituted eitherby a spiral or by a helix, which allows the length of the passage to begreater than a corresponding circumferential portion being disposed atsubstantially the same distance from a central portion of the rigidpartition as the spiral or helix;

the passage, when it consists of two parts, may be constituted of eithertwo overlapped spirals having the same center, or two overlapped helixeshaving the same axis;

the dimensions (length and/or cross section) of the passage for dampingliquid can be adjusted by simple mechanical means such as removal ofmaterial from at least one of the two parts of the rigid partition,appropriate processing, which may include molding to size, lapping,grinding, finishing, lathe-working, or the like, the insertion of a shimbetween the base and the cover of the rigid partition, or the rotationof one of these constituents in relation to the other, to adjust thecolumn of damping liquid to the desired frequencies for differentapplications.

The different processes for the adjustment of the dimension of thepassage for damping liquid, taken separately or in combination incertain cases where compatible, are as follows:

To change the length of the passage, it is possible:

to change the diameter of the boring where it opens onto rigidpartition, by appropriate processing, which may include boring, grindingand/or lathe-working. This process is applicable to a passage consistingof one or two parts, in the form of a spiral or spirals;

to offset the boring, in the case of a passage in two parts, in the formof spirals. The length is then adjusted independently over both parts ofthe passage;

to use the rotation of the cover in relation to the base of the rigidpartition, at the time of assembly, in the case of a passage for dampingliquid in one or two spiral parts The adjustment of the length is thenthe same for both spiral parts of the passage.

To change the cross section of the passage for damping liquid, it ispossible:

to perform a flat processing, such as, grinding or lathe-working, of atleast one of the assembly surfaces of the base and of the cover of therigid partition, which results in a reduction of the cross section ofthe passage, in one or two parts, in the form of a spiral or spirals ora helix or helixes, the adjustment of the two spiral or helicoidal partsthen being the same;

to perform an oblique grinding or lathe-working of at least one of theassembly surfaces of the base and of the cover of the rigid partition,which is advantageous for the reduction of the cross section of thepassage when it consists of two parts, in the form of spirals orhelixes, by making it possible to adopt a different adjustment for eachof the spirals or helixes;

the insertion of a flat shim between the base and the cover of the rigidpartition, which makes it possible to increase the cross section, aprocess which is applicable when the passage for the damping liquidconsists of one or two parts, in spirals or in helixes (the adjustmentof the two parts of the passage then being the same);

the insertion of an oblique shim between the base and the cover of therigid partition, which is advantageous for a passage in two parts, inthe form of a spiral or spirals or a helix or helixes, by making itpossible to adopt a different adjustment for the increase of the crosssection of each of the spirals or helixes. One aspect of the inventionresides broadly in an elastic, anti-vibration, isolation apparatushaving hydraulic damping, the apparatus for elastically mounting a firstcomponent to a second component, the apparatus comprising: anarrangement for mounting the apparatus on a first of the components, thearrangement for mounting being disposed at one portion of the apparatus;another arrangement for mounting the apparatus to a second of thecomponents, the second arrangement for mounting being disposed atanother portion of the apparatus; the first arrangement for mountinghaving bonded thereto an elastomeric component; the elastomericcomponent forming one end of the apparatus; a rigid partition disposedwithin the apparatus and separating the apparatus into at least a firstchamber and a second chamber, the first chamber being disposed betweenthe rigid partition and the elastomeric component, the first chamberbeing substantially filled with damping fluid and comprising a chamberin which damping fluid therein is subject to compressing and otherforces for varying the volume thereof, the first arrangement formounting and at least a portion of the elastomeric component beingdisposed for moving at least with relationship to the rigid partition;the rigid partition having two sides, a first side being disposedtowards the first chamber, and a second side being disposed towards thesecond chamber; the second chamber comprising an expansion chamber forat least accepting damping fluid from the first chamber, the secondchamber also being substantially filled with damping fluid; the rigidpartition having disposed therein at least one passage having dimensionsfor conducting damping fluid between the two chambers; the rigidpartition comprising at least two components, the at least one passageextending in at least one of the at least two components for passingdamping fluid between the first side and the second side of the rigidpartition; the at least one passage having a length dimensionsubstantially greater than a cross section dimension thereof; anarrangement for varying at least one dimension of the at least onepassage; and the dimension varying arrangement being chosen from atleast one member of the group consisting essentially of: a) at least onesurface of the rigid partition having been dimensionally adjusted byremoving at least a portion of the at least one surface duringmanufacture to obtain given dimensions; and b) an arrangement forreceiving shim between the first and second components of the rigidpartition, and also including a shim for insertion into the arrangementfor receiving the shim between the first and second components of therigid partition; the arrangement for varying dimensions of the passagebetween the two chambers being tuneable to desired dampingcharacteristics for tuning the elastic anti-vibration apparatus to atleast one given frequency characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics and variants of the invention are explained ingreater detail in the description accompanying the drawings, in which:

FIG. 1 is a schematic diagram of the elastic mounting with integratedhydraulic damping, and identifies the rigid partition which houses thepassage for damping liquid;

FIGS. 2a, 2b and 2c illustrate one particular configuration of the rigidpartition in which the passage for the damping liquid is realized in asingle part in the shape of a spiral, more particularly, FIG. 2a is asection view of the rigid partition, FIG. 2b is a top view of the baseand FIG. 2c is a bottom view of the cover;

FIGS. 3a, 3b, 3c, 3d, 3e, 3f and 3g show one variant of the rigidpartition in which the passage for the damping liquid is realized in twoparts having the shape of two overlapped helixes, with the safe axis;

FIG. 4 shows another variant of the rigid partition in which the passageis enlarged by a shim having a spiral cut therein, which shim isinserted between the two parts of the rigid partition;

FIG. 5a shows yet another variant of the rigid partition with an obliqueshim disposed between the two parts thereof;

FIG. 5b shows the base of the rigid partition of FIG. 5a, in plan;

FIG. 5c shows the cover of the rigid partition in plan from the topthereof;

FIG. 5d shows FIG. 5a with the oblique shim, in section;

FIG. 5e shows the base of the rigid partition with the oblique shimmounted thereon, as seen in plan from above;

FIG. 6 illustrates one particular configuration of the rigid partitionsimilar to FIG. 3b in which the passage for the damping liquid isrealized in the shape of an extended helix; and

FIG. 7 shows the base in plan with a dual spiral.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows, in vertical section, the elastic mounting with integratedhydraulic damping, and identifies the rigid partition 1 in the elasticmounting formed by a deformable thick conical membrane 2, designed tobear the load by strain in shearing of the elastomer compound of whichit is made, and which connects the internal rigid frame 3 to thestructure of the vehicle, such as, the chassis, and the external rigidframe 4 to the power unit, such as, the motor, of the vehicle.

The damping liquid fills the variable volume chamber 5 and an expansionspace 6 where a very low overpressure, that is, pressure above ambient,is maintained by deformation of the flexible membrane 7.

To provide damping during operation of the elastic mounting, the dampingliquid is transferred from the variable volume chamber 5 to theexpansion space 6, through the opening 9, via the passage 8 housed inthe rigid partition 1, and forming part thereof.

In the invention, the prefabricated rigid partition 1 is formed by twoassembled rigid elements, preferably made of polymer materials, eachmolded in its desired shape. The molding of these elements is preferablydone using conventional processes of the polymer transformationindustry, as is well known in the prior art.

One spiral is shown in FIG. 1; in an alternative embodiment analogous tothe one of FIG. 7, more than one spiral could be realized.

FIGS. 2a, 2b and 2c illustrate one particular configuration of the rigidpartition 1 in which the passage for damping liquid 8 manifests itselfas a single passage having the shape of a spiral in the partition 1.

FIG. 2a is a cross section of the rigid partition 1, comprising a base10 and a cover 11. This rigid partition 1 differs from the rigidpartition in FIG. 1, where, in FIG. 1, as a function of the desiredcross section of the passage for damping liquid, the base 10 and thecover 11 of the rigid partition 1 can have the same geometry of thepassage 8. The only substantial differences between the base 10 and thecover 11 are that the base 10 has pins in relief, protruding therefromand the cover 11 has recessed housings or holes in locationscorresponding to the pins for accepting same The positions of theopening 9 and the boring 11a are also different in the base 10 and thecover 11.

In the illustrated variant, in FIG. 2a of the rigid partition 1, thebase 10 houses the entire passage for damping liquid 8, while the cover11 has a flat surface which, during assembly, comes into contact withthe base 10.

Communication between the damping liquid circuit and the variable volumechamber takes place via the opening 9 located at the beginning of thepassage 8, while communication with the expansion space takes place viaa ground, variable diameter C of 1, the boring 11a in the rigidpartition 1, both in the base 10 and in the cover 11, i.e., suchgrinding being possible after assembly of these two components of therigid partition 1.

The axis of the variable diameter C of the boring 11a in the rigidpartition 1 does not necessarily coincide with the axis of thehydroelastic mounting, since its axial offset does not modify the volumeof damping liquid displaced by the deformation of the variable volumechamber.

FIG. 2b shows a plan view of the base 10 of the rigid partition 1 beforeassembly with the cover 11. It shows the spiral shape of the dampingliquid passage 8, the length of which is greater than one circumference,and the eight assembly pins 12 shown here, as non-limiting examples,which fit into recessed housings, with the same number and arrangement,in the cover 11. Other methods of assembly well known in the art, suchas, bonding or other fastening by a cementing compound may be used.

The grinding or lathe-working of the diameter C of the boring 11a whichis tangentially disposed with respect to the spiral, constituting all ofone-half of the passage for damping liquid 8, depending on theconfiguration selected for the cover 11, is advantageously performed onthe rigid partition 1 after assembly; the mass production of the rigidpartition 1 produced by molding a polymer such as a 6-6 polyamidereinforced with glass fibers or glass spheres, can be highly automated.

FIG. 2c shows, looking at the bottom thereof, the variant of the cover11 of the rigid partition 1 exhibiting one flat surface which, duringassembly, is placed in contact with the base 10. This figure illustratesthe arrangement of the recessed housings 13, the number of which is thesame as the number of pins 12 on the base 10.

The adjustment of the hydroelastic mounting to the desired damping, bythe selection of the shape and size of the passage for damping liquid 8,makes it possible to respond to given utilization conditions such as,for example, the vibration frequency introduced by the masses notsuspended by the suspension (or by the motor when the hydroelasticmounting is designed for the suspension of a truck cab).

With all rigidities otherwise equal, the manufacturer of hydroelasticmountings can change the mass of the damping liquid column to shift thefrequency at which the apparent maximum damping is produced, by phasedisplacement between the speed and the acceleration, while measuringforced vibrations.

An increase in the diameter C of the boring 11a being cut into the rigidpartition 1, with a constant cross section of the column of dampingliquid, reduces the length of the spiral-shape passage 8; the mass andthe surface area of the boundary layer of the column of damping liquidare reduced proportionally. The result is an increase of the frequencyat which the damping is maximum, accompanied by a reduction of thedamping rate and the phase displacement.

The reverse results, obviously, are observed for a reduction of thediameter C of the boring 11a in the rigid partition 1, with a constantcross section of the column of damping liquid.

A reduction of the depth of the passage for damping liquid 8 can beachieved by removing a portion of the assembly plane of the base 10, forexample, by spot facing, (according to the embodiment of FIG. 2a),and/or the cover 11, (according to the embodiment of FIG. 1), of therigid partition 1. This has the effect of reducing the mass of thedamping liquid column, similar to that caused by the increase in thediameter C of the boring 11a in the rigid partition 1, but with areduction of the surface of the boundary layer in contact with the wallsof the passage for damping liquid 8. Corresponding to equal displacementof the deformable walls, constituted by the thick conical membrane 2 ofthe hydroelastic mounting, is a given instantaneous flow and aninversely proportional acceleration of the displacements of the dampingliquid in the column with a reduced cross section.

The relative effect of the damping and the phase displacement increaseswith an increase in frequency, in contrast to the results obtained bymodification of the diameter C of the boring 11a in the rigid partition1.

If the flat grinding or lathe-working of the assembly surface of thebase 10 and of the cover 11 of the rigid partition 1 makes it possibleto reduce the cross section of the passage for damping liquid 8, thereare applications where, when the opposite effect is desired, it isdesirable to increase the cross section of the passage. To do this, aflat shim is inserted between the base 10 and the cover 11 of the rigidpartition 1, as in FIG. 4. The thickness of the flat shim will,obviously, be limited by the space available between the variable volumechamber and the expansion space.

The combination of the adjustments of the diameter C of the boring 11aand of the depth of the passage for damping liquid 8 therefore makespossible a very precise adjustment of the maximum efficiency of thehydroelastic mounting as a function of the conditions of utilization.

In applications which require an expansion of the frequency ranges, avariant configuration (not shown) of the damping liquid passage allowstwo different adjustments, thanks to the realization of the passage intwo parts, in the shape of spirals, wound one inside the other, as shownin FIG. 7, by offsetting the boring C, which will intersect the firstspiral along a developed length less than that along which it intersectsthe second spiral. For this reason, the two resonant effects, combinedwith the maximum displacements, will allow an optimal damping over awider range of frequencies.

It is also possible, for certain particular applications, to realize theconfiguration of the passage for damping liquid 8 in two spirals, anadjustment with two maximum damping values.

This effect can be obtained either by offsetting the boring, asindicated above, or by modification of the cross sections of the twospiral shaped parts of the passage for damping liquid 8.

A reduction of the cross section of at least one of the two parts of thepassage 8 is obtained by oblique grinding or lathe-working, as shown inFIG. 5d, of the assembly surface of the base 10 and of the cover 11 ofthe rigid partition 1, while an increase of the cross section of thepassage 8 is made possible by the insertion during assembly of anoblique shim between the base 10 and the cover 11 of the rigidpartition 1. These processes make possible the modification of the crosssection of one of the spiral shaped parts of the passage for dampingliquid 8, independently of the other part. If the same modification ofthe cross section is desired for both spiral shaped parts of the dampingliquid passage 8, there are two possibilities open to the design of thepart: a flat grinding or lathe-working of the assembly surface of thebase 10 and of the cover 11 makes it possible to reduce, simultaneously,the cross section of the two spiral shaped parts of the passage 8, whilethe insertion of a flat shim between the base 10 and the cover 11 of therigid partition 1 during assembly will make it possible to increasesimultaneously the cross section of the two spiral shaped parts of thepassage 8.

As in the case where the passage consists of a single part in the shapeof a spiral, it is possible to change the length or the two spiralshaped parts of the passage 8 by grinding or lath working the boringwhere they empty onto the rigid partition 1. The manufacturer ofhydroelastic mountings, on account of the design of the rigid partition1, can therefore, change three parameters of the circuit for dampingliquid, which will allow him to make the adaptations during assembly ofthe components of the hydroelastic mounting, for several types of motorsor suspensions, with different loads, while being able to benefit fromthe advantages of mass production of the components, i.e., a reducedproduction cost and a greater adaptability to evolutions ofcharacteristics, the components being all identical for the differentmodels of a given product, with the exception of the rigid partition 1which is adjustable, and which can also be mass produced.

FIGS. 3a, 3b, 3c, 3d, 3e, 3f and 3g show one variant of the rigidpartition 1 in which the passage for damping liquid 8 no longer consistsof two coiled spirals, but two helixes, show cylindrically here, butthey can also be conical, overlapped one inside the other, and thecoiling over more than one revolution is obtained by a slight slope ofeach of the helicoidal parts the passage for damping liquid 8 inrelation to the axis 10a of the rigid partition 10

FIG. 3a shows a cross section along BOB' in FIG. 3b of the rigidpartition 1 in which the cover 11 is shown with the same generalgeometry as the base 10, the main difference between these twocomponents being the presence of the assembly pins, e.g., located on thebase 10, and designed to fit into the corresponding recessed housings orholes 13 in the cover 11.

FIG. 3b is a schematic diagram of the position of the two helicoidalparts 8a and 8b of the passage for damping liquid in the base 10 of therigid partition 1 which contains the assembly pins 12.

Various methods make it possible to modify, simultaneously orindependently, the length and/or cross section of the double column ofdamping liquid and, consequently, to change the damping characteristicsof the hydroelastic mounting.

Thus, for example, an angular shift during assembly of the base 10 andof the cover 11 of the rigid partition 1, e.g., a rotation of the base10 by one or more pins 12 in relation to the corresponding recessedhousings or holes 13 on the cover 11, simultaneously modifies the crosssection of a portion of the two helicoidal parts 8a and 8b of thepassage for damping liquid, a well as the useful length of the column ofdamping liquid between the two openings 9a and 9b, and theircorresponding openings in the cover 11, thereby allowing a differentadjustment both of frequency and phase displacement, for the apparentdamping of the dynamic rigidity exhibited by the hydroelastic mounting.

This means of adjustment by angular shifting of the base 10 and of thecover 11 of the rigid partition 1, with respect to one another, does notchange the external dimensions of the rigid partition.

Other adjustment possibilities consist of modifying the thickness of therigid partition 1 and are limited to values compatible with theinstallation of the rigid partition in the body of the hydroelasticmounting.

To simultaneously reduce the cross section of the two helicoidal parts8a and 8b of the passage for damping liquid, it is possible to perform aflat lathe-working of the assembly surface of the base 10 and of thecover 11 of the rigid partition 1, e.g., by lathe-working or grindingthe surface of the cover 11 with the preferably, blind holes or recessedhousings designed to receive the assembly pins 12.

The insertion between the base 10 and the cover 11 of the rigidpartition 1, during assembly, of a flat shim, such as shown in FIG. 4,makes it possible, by contrast, to simultaneously increase a portion ofthe cross section of the two helicoidal parts 8a and 8b of the passagefor damping liquid.

It is also possible to change, separately, the dimensions of the twohelicoidal parts 8a and 8b of the passage for the damping liquid, eitherby performing an oblique grinding or lathe-working of the assemblysurface of the base 10 and of the cover 11 of the rigid partition 1, theeffect of which may be to reduce a portion of the cross section as wellas the useful length of the double column of damping liquid. Thisarrangement provides a means to obtain different values for each of thetwo helicoidal parts 8a and 8b of the passage for damping liquid.Alternatively, an oblique shim with a slight slope, can be insertedbetween the base 10 and the cover 11, during assembly of the rigidpartition 1, the effect of which may be to increase the cross sectionand the useful length of the double column of damping liquid todifferent values for each of the two helicoidal parts 8a and 8b of thepassage for damping liquid.

The rigid partition 1 with a helicoidal passage can be simplified in avariant (not shown) comprising a passage consisting of a single part,for certain applications. The processes to adjust the dimensions of thehelicoidal passage are then limited to the angular shifting of the base10 in relation to the cover 11 of the rigid partition, during assembly,to the flat grinding or lathe-working of the assembly surface of thebase 10 and of the cover 11 or to the insertion, between the base 10 andthe cover 11, of a flat shim of a thickness limited to values compatiblewith the installation of the rigid partition 1 in the hydroelasticmounting.

One embodiment of the hydroelastic mounting, as shown in FIG. 2a, in theconfiguration where the rigid partition 1 includes a one-part passagefor the damping liquid 8 is described below, the adjustment methodselected being the grinding or lathe-working of the boring 11a.

FIG. 3c shows another embodiment of the section through COD of FIG. 3b.In this figure, one hole in base 10 is denoted as 19b', and this hole19b' is connected through a passage 18b' in base 10, and through acorresponding passage in cover 11 to a hole 19b" in the cover 11.

FIG. 3d shows a variant of FIG. 3b with reference numeral denotations ofFIG. 3c, and section lines BOB', COD, COB' and BOD.

FIG. 3e shows a section through FIG. 3d along the line BOB'. The rigidpartition 1 in this figure shows only one passage which is composed of18b' and 18b" for clarity.

FIG. 3f shows a section COB' of FIG. 3d. This Figure, 3f, shows only onepassage which is the connection of the opening 19b' with the passage18b". Any other passages in the rigid partition 1 have been omitted forpurposes of clarity.

FIG. 3g shows a section BOD through FIG. 3d. As in FIGS. 3e and 3f, onlyone passage is shown. As in all of FIGS. 3e, 3f and 3g, the passages18b' and 18b''of the two parts, base 10 and cover 11, are shown bydotted lines.

FIG. 4 shows a shim 20 disposed between the base 10 and cover 11. Thisshim has a spiral cut therein which increases the cross section of thepassage 8 in the base 10.

FIG. 5a shows an alternative embodiment of the rigid partition 1. Inthis embodiment, the rigid partition 1 is made up lathe-worked or groundsuch that at least one of the base 10' or Of a base 10' the cover 11' issomewhat wedge shaped. Between these two original portions of the rigidpartition 10, that is, the base 10' and the cover 11', an oblique shim120 is disposed. This oblique shim 120 has holes therein which acceptthe pins 21 of the base 10' such that the pins 21 protrude through theoblique shim 120 into blind holes in the cover 11'. For simplicity andclarity, the pins 21 and the holes are not shown. The base 10' has ahole 119b' in the bottom surface thereof which connects to a passage118b'. This passage 118b' is aligned with a hole 122 in the oblique shim120 (shown in FIG. 5a). This hole 122 in the shim 120 is preferablysomewhat larger than the opening which passage 118b' makes on the uppersurface of the base 10'. This hole 122 in the oblique shim 120 connectspassage 118b' to a passage 118b " in the cover 11'. This hole 122 in theoblique shim 120 is also preferably somewhat larger than the openingwhich the passage 118b" makes in the lower surface of the cover 11'.This passage 118b" connects with a hole 119b" in the upper surface ofthe cover 11'. Only one passage comprises 118b', the hole 122 and thepassage 118b" of the preferably two passages in the rigid partition 1 isshown in FIG. 5a.

FIG. 5b shows a top view of the base 10' in the rigid partition 1 asshown in FIG. 5a. As can be seen from this figure, the passage 118b' ofthe base 10' is shorter than the corresponding passage in FIG. 3d.

FIG. 5c shows a top view of the cover 11' with only one of the holes,hole 119b", shown therein. Connected to this hole 119b" is the passage118b", The cover 11' is shown rotated in the position for assembly inthe rigid partition 1, such that, the opening of 118b''is aligned withthe hole 122 in the oblique shim 120, as shown in FIG. 5a.

FIG. 5d shows the oblique shim 120 in section in the rigid partition 1.The oblique shim 120 is also preferably made of a plastic material whichmay preferably be similar to the material of the base 10' and the cover11'. However, other materials may be used for the oblique shim 120 thanfor the other parts of the rigid partition 1.

FIG. 5e shows the oblique shim 120 placed on the upper surface of thebase 10'. As can be seen, the hole 122 in the shim is somewhat largerthan the opening formed by the passage 118b' in the base 10'.

FIG. 6 shows a helicoidal passage in the base 10, which when assembledwith a similar cover 11, extends more than one revolution around thepartition 1.

FIG. 7 shows a base 10 with two spiral passages 8a and 8b disposed inpartition 1. The boring C is offset from the center of base 10 toprovide damping at two frequencies.

The hydroelastic mounting is produced by assembling the components,manufactured separately, in the following sequence:

first of all, in a molding operation common in the rubber industry, theassembly constituting the internal rigid frame, the elastomeric conicalmembrane and the external rigid frame is made on a press, followed by anintimate bonding of these three elements simultaneous with thevulcanization of the elastomer compound;

independently, in a molding operation, the flexible wall which enclosesthe expansion space is realized;

the components, base and cover, of the rigid partition are alsofabricated, these components being realized by molding polymer material,possibly reinforced, in molds of the desired shapes for the passage forthe damping liquid and to produce the pins or the recessed assemblyhousings, in the base or the cover, respectively;

the subsequent operation comprises the assembly of the base and thecover to form a closed unit or cassette, this assembly beingadvantageously produced by ultrasonic welding;

the boring where the spiral or helicoidal damping passage or passagesempty is then ground or lathe-worked to adjust its length;

the constituent elements of the hydroelastic mounting are thenassembled, and a crimping operation completes the assembly in the formof a rigid casing. If the crimping is performed using the so-called"submarine" method or technique, the filling of the hydroelasticmounting with the damping liquid takes place during the same operation.The "submarine" method is described in U.S. Pat. No. 4,893,799 (AttorneyDocket No. NHL-KLE-0l), entitled "Vibration Isolation Apparatus",corresponding to French Patent Application No. 8700762, filed Jan. 23,1987, which is hereby expressly incorporated by reference as if theentire contents thereof were fully set forth herein.

On page 5, line 16, to page 6, line 11, of U.S. Pat. No. 4,893,799,there is stated therein the following:

"In another aspect, the invention features a process for manufacture ofa vibration isolation apparatus. The process comprises the steps of: a)providing a first subassembly, the first subassembly comprising aninternal tube member, a first intermediate tube member and firstflexible lateral end wall apparatus, the internal and the firstintermediate tube members being maintained in spaced and concentricalignment by their mutual attachment to the first flexible lateral endwall apparatus; b) providing a second subassembly, the secondsubassembly comprising an external tube member, a second intermediatetube member and second flexible lateral end wall apparatus, the externaland second intermediate tube members being maintained in spaced andconcentric alignment by their mutual attachment to second flexiblelateral end wall apparatus; c) submerging the first and secondsubassemblies in a bath of a damping fluid; d) removing substantiallyall air bubbles from the submerged first and second subassemblies; e)concentrically and axially mating the first and second subassemblies,such that, in the assembled configuration, the internal tube member ispositioned substantially concentric with and within the secondintermediate tube member, the second intermediate tube member ispositioned substantially concentric with and within the fistintermediate tube member, and the first intermediate tube member isposition substantially concentric with and within the external tubemember; and f) maintaining the concentrically and axially mated firstand second subassemblies in the assembled configuration."

On page 17, line 6 to line 29, U.S. Pat. No. 4,893,799 there is statedtherein substantially the following:

A preferred process for the fabrication of such a device consists ofperforming the following operations:

The two assemblies, illustrated, are produced by pressure casting with aheat treatment which simultaneously vulcanizes the elastomer compoundand produces a bond between the elastomer compounds and the rigidinternal, intermediate and external tubes, which act as frameworks,according to a process conventionally used in the rubber transformationindustry.

An assembly operation, using a so-called "submarine" assembly press,makes it possible to join the tube assemblies from which all the airbubbles have been expelled. The end of the rigid intermediate tube isfreely engaged over the rigid internal tube, while the preferablybevelled end of the rigid intermediate tube is engaged in the rigidexternal tube, until the thin layer of elastomer compound and theelastomer compound film prevent further penetration.

A fitting force is exerted, then, by staggered circular stops which areprovided on the external edge of each of the rigid tubes, at a regulatedrate, so that an appropriate internal pressure is maintained by thecharacteristic rigidity of the elastic lateral walls. (end ofsubstantial quote)

A variant filling of the hydroelastic mounting with the damping liquidconsists of using a vacuum technique in the vessel by providing alateral boring in a rigid casing, which is then sealed by a rivet.

The anti-vibration isolation device with integrated hydraulic dampingwhich is the object of the invention and is designed to provide elasticsuspension of drive units of vehicles or truck cabs has the advantage,over the solutions of the prior art, that it makes it possible, usingidentical components; to create an extended range of hydroelasticmountings adapted to each application, because of the insertion, duringassembly, of a rigid partition comprising at least one damping liquidpassage adapted, or adaptable, in length and cross section, to thedamping function to be performed.

Because of this design, it is therefore possible to realizeeconomically, even in limited quantities, a wide variety of hydroelasticmountings with integrated hydraulic damping, which are perfectly adaptedto the requirements of individual applications.

In summing up, the elastic anti-vibration, isolation, apparatus whichhas integrated hydraulic damping therein comprises an elastic mounting.This elastic mounting has a thick conical membrane 2 made of anelastomeric compound. This thick conical membrane is bonded to a rigidinternal frame 3 and to a rigid external frame 4 and crimped in a rigidcasing. This structure encloses a damping liquid acting such that theinertia of the column of damping liquid provides a damping functionwhich has desirable damping characteristics. The length of this columnof damping liquid is very long in relationship to its average crosssection. The rigid partition 1 which separates the variable volumecylinder 5 from the expansion space 6 has a passage 8 which forms theinertial column and receives the damping fluid. The passage 8 is formedby one or two parts. The dimensions of these parts can be adjusted bylathe-working or grinding of at least one of these parts, that is, thebase 10 or the cover 11 of the rigid partition 1. The dimensions of thepassage can be adjusted during manufacture either as an alternative tothe lathe-working or by the lathe-working of the base 10 or the cover 11to form a slightly wedge shaped configuration and then by the insertionof at least one shim between the base 10 and the cover 11. The twoalternatives, the first being lathe-working at least one of the base 10or cover 11, and the second being the insertion of shims therebetween,make it possible, using a set of substantially identically shapedcomponents, which comprise the base 10 and the cover 11, to provide aseries of hydroelastic mountings with different damping characteristics,which may be adapted to the utilization frequencies of the isolationapparatus, or, in other words, the working of the components 10 and 11allow for the use of substantially standard components, which can thenbe adjusted to provide the desired damping characteristics for theisolation apparatus.

Another aspect of the invention resides in that the base 10 and cover11, which constitute the rigid partition 1, have substantially similargeometry. This geometry may include the outer portions of the base 10and the cover 11. Alternatively, the base 10 and the cover 11 may have apassage made up of one or two parts for receiving the damping fluid. Thebase 10 also has assembly pins 12 designed to fit into correspondingholes or recesses 13 in the cover 11. In the event that the spiralpassage is distributed between the base 10 and the cover 11, these partsare substantially identical.

Another further aspect of the invention relates to that only the base 10of the rigid partition 1 has a passage for damping fluid therein. Thecover 11 has a flat surface which, during assembly, is placed in contactwith the upper surface of the base 10. The cover 11 is held in place bythe pins 12 protruding upwardly from the base 10 into the correspondingholes 13 of the cover 11.

Yet another aspect of the invention relates to the fact that the rigidpartition 1 includes a passage 8 which is made up of either one or twoparts. At least one of these parts has a length which is greater thanthat of a corresponding length of one complete revolution around therigid partition 1. This configuration can be seen in FIG. 6, where thepassage formed by the base 10 and the corresponding passage in the cover11 have a length, when assembled, of more than one revolution. Also, inFIG. 2b, the spiral shown therein, which comprises the passage 8,extends more than one revolution around the rigid partition 1.

Still yet a further aspect of the invention provides a passage 8 for thedamping fluid comprising a single spiral, as shown in FIG. 2b.

Still yet another aspect of the invention provides that the passage 8comprises a single helix.

Yet still another aspect of the invention provides that the rigidpartition 1 has a passage which is made up of two parts 8a and 8b. Inthis case, there are two passages in the shape of overlapping spirals,such as indicated in FIG. 7. These overlapping spirals emanate from asubstantially similar central location in the rigid partition 1.

Yet a further aspect of the invention provides for two overlappinghelixes which form at least two passages in the rigid partition 1, asshown in FIG. 3a. These two overlapping helixes are preferably formedabout the same axis in substantially the middle portion of the rigidpartition 1. There may be, in an alternative embodiment, more than twohelixes. Moreover, even in this case, these helixes preferably also areformed about the same central axis 10a.

Still a further aspect of the invention provides for the regulation ofthe dimensions of the passage 8 which may be for in one or two parts,such that the shape of a spiral or spirals is done by boring a hole 11ahaving a diameter C. This boring 11a is placed to vary the shape or thelength of the spirals to adjust these to a desired characteristic oflength or cross section. This hole 11a is placed in the rigid partition1 where the passage 8 is desired to empty from the rigid partition 1.

Yet still another aspect of the invention provides that the boring orhole 11a of the immediately above paragraph, as shown in FIG. 7, can beoffset in such a way that if there are two spirally shaped parts 8a and8b, which make up the passage in the rigid partition 1, the lengthsthereof can be regulated independently one of the other. By regulatingthe dimensions or each of the two spirally shaped parts 8a and 8bindependently, the damping of the isolation apparatus can be adjustedfor two difference frequencies, one resulting from each of the spirallyshaped parts 8a and 8b.

Still an additional aspect of the invention provides that the helicoidalor helical parts, 8a and 8b of FIG. 3b, which make up the passage forthe flow of damping fluid between the chambers, can be adjusted byangular rotation during assembly or the base 10 with respect to thecover 11. The base 10 and the cover 11 can be adjusted by the rotationof one with respect to the other so that a difference set of pins 12 inthe base 10 are aligned with a different one of the holes 13 of thecover 11. Because the openings, in the cover 11 and the base 10, whichconnect the passages of one with the other, extend over at least two ofthe pins 12, at least two positions of the cover 11 with respect to thebase 10 can be attained. If a greater number of adjustments arerequired, a greater number of pins 12 than the six shown in the figurescan be used, which will allow for indexing of the cover 11 with respectto the base 10 by a greater number of rotational displacementstherebetween. For example, if twelve pins are used instead of the six inFIG. 6, then at least four positions can be made operationally availablefor adjustment of the cover 11 with respect to the base 10. Thisadjustment would change the length and parts of the cross sections ofthe passages extending through the rigid partition 1.

Still yet another additional aspect of the invention provides thecapability of changing the cross sections and/or also the lengths of thetwo spiral or two helical parts 8a and 8b of the passage 8 by theoblique removal of at least one of the mating surfaces of the base 10and the cover 11. The two spiral or two helical parts can thus be variedto achieve optimum damping at least two difference frequencies.

Yet still another additional aspect of the invention relating to theelastic, anti-vibration, isolation apparatus with integrated hydraulicdamping provides that the adjustment of the cross sections of theconnection or connections between the two sides of the rigid partition 1can be achieved by lathe-working or grinding of at least one of thesurfaces which are mated between the base 10 to the cover 11. By suchlathe-working or grinding, the spiral or spirals or helix or helixes canhave their cross sections adjusted simultaneously.

Yet still a further additional aspect of the invention provides that thecross section of the passage in the rigid partition, which may be formedas a spiral or spirals or as a helix or helixes, can be adjusted by theinsertion, during assembly, of a flat shim between the base 10 and thecover 11. This flat shim provides for the simultaneous adjustment of atleast the length of, and even in some embodiments, portions of the crosssectional area of the at least two passages, when there are two or morepassages in the rigid partition 1.

The invention as described hereinabove in the context of the preferredembodiments is not to be taken as limited to all of the provided detailsthereof, since modifications and variations thereof may be made withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. An elastic antivibration isolation apparatushaving hydraulic damping, said isolation apparatus for beinginterposable between a first component and a second component whichvibrates relative to said first component and comprising:a substantiallyrigid external frame comprising a first mounting means for mounting saidisolation apparatus on said first component; second mounting means formounting said isolation apparatus on said second component, said secondmounting means comprising a substantially rigid member; an elastomericelement interconnecting said substantially rigid external frame and saidsecond mounting means and providing relative movement therebetweenthrough flexure of said elastomeric element; an internal cavity locatedsubstantially within said external frame; a substantially rigidpartition substantially dividing said internal cavity into a firstchamber and a second chamber, the volume of said first chamber beingalterable through flexure of said elastomeric element, said secondchamber comprising an expansion space, said first chamber and saidexpansion space being substantially filled with a damping fluid, andsaid substantially rigid partition comprising at least one throughgoingpassage for providing communication of said damping fluid between saidfirst chamber and said expansion space; substantially said rigidpartition comprising: a base member; and a cover member; said base andcover members having opposing faces; at least one of said base and covermembers having at least two spiral grooves formed on its correspondingopposing face; each of said at least two spiral grooves separatelycomprising at least a portion of said throughgoing passage, each of saidat least two spiral grooves being for providing said communication ofsaid damping fluid independently of any other of said at least twospiral grooves, each of said at least two spiral grooves comprising afirst end and a second end, said first end of each of said at least twospiral grooves communicating solely with said first chamber and saidsecond end of each of said at least two spiral grooves communicatingsolely with said second chamber; and means for varying the length of atleast one of said at least two spiral grooves independently of thelength of any other of said at least two spiral grooves to thereby tunethe damping characteristics of said elastic antivibration isolationapparatus to at least one frequency characteristic; said length varyingmeans comprising at least one hole provided in at least one of said baseand cover members, proximate the center thereof, and intersecting eachof said at least two spiral grooves at an inwardmost extremity thereof,the diameter and position of said at least one hole determining saidlength of each of said at least two spiral grooves and, at least inpart, the damping characteristics of said elastic antivibrationisolation apparatus.
 2. An antivibration isolation apparatus accordingto claim 1, wherein said hole is disposed tangentially with respect toat least one of said at least two spiral grooves.
 3. An antivibrationisolation apparatus according to claim 2, wherein said at least one ofsaid at least two spiral grooves extends more than one full revolutionwithin said rigid partition.
 4. An antivibration isolation apparatusaccording to claim 2, wherein said hole is asymmetrically positionedwith respect to said at least two spiral grooves such that the effectivelengths of said at least two spiral grooves substantially differ fromone another.
 5. An antivibration isolation apparatus according to claim4, wherein said at least one of said at least two spiral grooves extendsmore than one full revolution within said rigid partition.
 6. Theantivibration isolation apparatus according to claim 5, furtherincluding means for varying the length of two of said at least twospiral grooves, said length varying means comprising said at least onehole provided in at least one of said base and cover members.
 7. Anantivibration isolation apparatus according to claim 1 wherein said atleast one of said at least two spiral grooves extends more than one fullrevolution within said rigid partition.
 8. A method for tuning aplurality of elastic antivibration isolation apparatuses havinghydraulic damping, each of said plurality having identical components,said plurality of isolation apparatuses comprising different groups,each of said groups having different frequency characteristics, saidisolation apparatus for being interposable between a first component anda second component which vibrates relative to said first component, eachsaid elastic antivibration isolation apparatus comprising:asubstantially rigid external frame comprising a first mounting means formounting said isolation apparatus on said first component; a secondmounting means for mounting said isolation apparatus on said secondcomponent, said second mounting means comprising a substantially rigidmember; an elastomeric element interconnecting said substantially rigidexternal frame and said second mounting means and providing relativemovement therebetween through flexure of said elastomeric element; aninternal cavity located substantially within said external frame; asubstantially rigid partition substantially dividing said internalcavity into a first chamber and a second chamber, and volume of saidfirst chamber being alterable through flexure of said elastomericelement, said second chamber comprising an expansion space, said firstchamber and said expansion space being substantially filled with adamping fluid, and said substantially rigid partition comprising atleast one throughgoing passage for providing communication of saiddamping fluid between said first chamber and said expansion space; saidsubstantially rigid partition comprising:a base member; and a covermember; said base and cover members having opposing faces; at least oneof said base and cover members having at least one spiral groove formedon its corresponding opposing face and comprising a portion of saidthroughgoing passage; said at least one spiral extending around morethan one full revolution and said method comprising the steps of:starting with identical components; assembling the identical componentsof the base members and the cover members to form different groups ofsaid substantially rigid partitions;machining a hole having at least oneof: a different diameter and a different location in each of thedifferent groups of said substantially rigid partitions to vary thelength of said at least one spiral groove in a plurality of saididentical components during manufacture; assembling during manufactureeach of said different groups elastic antivibration isolationapparatuses to tune the damping characteristics of different groups ofsaid elastic antivibration isolation apparatus to at least one differentfrequency; and said at least one spiral groove comprising at least twogrooves in the form of a double spiral.
 9. The method according to claim8, including positioning said hole asymmetrically with respect to saidat least two spiral grooves forming said double spiral, such that theeffective lengths of said at least two spiral grooves substantiallydiffer from one another.
 10. The method according to claim 8, whereinsaid at least one of said at least two spiral grooves extends more thanone full revolution within said rigid partition.
 11. The methodaccording to claim 8, wherein said hole is disposed tangentially withrespect to at least one of said at least two spiral grooves.